The present invention relates to enhanced structured fuel compositions for use in jet, turbine, diesel, gasoline, and other combustion systems. More particularly, the present invention relates to fuel compositions using viscous hydrocarbons, which are substantially neutral pH, and which employ a silicon based combustion catalyst.
International patent application Nos. PCT/US95/02691, PCT/US95/06758, and PCT/US96/09653, are incorporated in their entirety herein by reference, and disclose fuel compositions and combustion techniques for achieving vapor phase combustion based on an enhanced combustion structure (xe2x80x9cECSxe2x80x9d). This enhanced combustion structure includes a combustible metallic and free radical generating oxygenated compound. It has been found that such free radical generating oxygenates include C2-C12 aldehydes, aldehydic acids, C2-C12 ethers, C1-C15 alcohols, C2-C12 oxides, C3-C15 ketones, ketonic acids, C3-C15 esters, othroesters, C3-C12 diesters, C5-C12 phenols, C5-C20 glycol ethers, C2-C12 glycols, C3-C20 alkyl carbonates, C3-C20 dialkyl carbonates, C3-C20 di-carbonates, C1 to C20 organic and inorganic peroxides, hydroperoxides, carboxylic acids, amines, nitrates, di-nitrates, oxalates, phenols, acetic acids, boric acids, orthoborates, hydroxyacids, orthoacids, anhydrides, acetates, acetyls, formic acids, nitrates, di-nitrates, nitro-ethers, which can meet minimum burning velocity (BV) and latent heats of vaporization (LHV) requirements of aforementioned PCT Applications. Specific compounds can be found in detail in Organic Chemistry 6th Ed, T. W. G. Solomons, John Wiley and Sons, N.Y., (1995), Physical Chemistry, 5th Ed, P. W. Atkins, Oxford University Press, U.K. (1994), Physical Organic Chemistry, 2 Ed, N. S. Issacs, John Wiley and Sons, N.Y. (1995) and Lange""s Handbook of Chemistry, 14th Ed, J. A. Dean, McGraw-Hill, N.Y. (1992), and their minimum BV/LHV requirements in aforementioned PCT Applications, which are herein by incorporated by reference.
Said enhanced combustion structure oxygenates, when in combination with a combustible non-lead metal or non-metal (as set forth below), exhibit high heats of enthalpy capable, improved combustion, thermal efficiency, fuel economy, and power. Of particularly interest to this invention are the enhanced combustion struture oxygenates of symmetrical dialkyl carbonates, especially dimethyl and diethyl carbonates.
However, it has been reported symmetrical dialkyl carbonates, such as dimethyl carbonate can be problematical fuel additives due to their potential instability in fuel compositions, which can result in undesired hydrolysis in acidic and aqueous environments. See EPO Application #91306278.2 Karas. Thus, it would be reasonable to expect fuels containing lower dialkyl carbonates to store and perform optimally only when in moderately strong or strongly alkaline environments, i.e., pH""s exceeding 11 or more. Fuels having pH""s lower than 11, e.g. moderately alkaline, neutral and acidic would be expected to be problematic.
In addition, conventional thinking and regulatory standards encourage the utilization of more refined less viscous base fuel hydrocarbons. The longer chain or more complex hydrocarbons, e.g., heavy oils, heavy fuel oils, diesels, etc., are typically not preferred as fuels due to handling, emission and combustion concerns.
Summary of the Invention A primary object of the present invention is the development and utilization of fuels having enhanced combustion structure which have increased stability. A further object of the present invention is the development of enhanced combustion structured in which the base fuel may be more viscous, or not as highly refined, as now required to meet minimum fuel standards. A further object is the employment of a co-metallic catalyst, which further enhances the combustion structure of the DMC and metal/non-metals component, further improving thermal efficiency, fuel economy, power and emissions.
In accordance therewith, the substantially non-alkaline fuel compositions of the present invention exhibits improved stability, with no apparent hydrolysis after storage for six months or more. In addition, the presence of lower dialkyl carbonates and metals in the fuel compositions of the present invention allows for the use of highly viscous base fuels.
The improved fuels described herein contain a base hydrocarbon fuel or propellant (including hydrogen) co-fuel, as provided in the PCT applications referenced above. Such co-fuels may be viscous, moderately viscous, or highly viscous (e.g. having viscosities outside industry standards). Said viscous fuels are combined with high energy non-lead metallic or non-metallics (presented below), together with symmetrical dialkyl carbonates, e.g., dimethyl or diethyl carbonate, and preferably a silicon co-metallic combustion catalyst. When the fuel compositions of the present invention are then constructed to a weakly alkaline (7.5 to 11.0 pH), substantially neutral (6.5 to 7.5 pH), or acidic (4.5 to 6.5 pH), whether or not water is present, they exhibit improved stability with no substantial hydrolytic propensity.